On Sep 1, 2009, at 3:13 PM, Erik Iverson wrote:
We will need a reproducible example! Please give us R commands that
display the behavior you're observing:
For example,
I am having trouble understanding the as.Date function. When I
input 39939, I would like to get "06.05.2009", but when I try it, I
get
as.Date(39939)
Error in as.Date.numeric(39939) : 'origin' must be supplied
I looked up what origin Excel uses for its' dates, and it seems like
it might be January 1, 1900, so I tried
as.Date(39939, origin = "1900-01-01")
[1] "2009-05-08"
Then we will much better be able to help you, because we will be
able to paste your commands into R and see the results and make
changes.
But this still seems to be off by two days. So did you really mean
"06.05", or "08.05"?
One of the two day discrepancy is because the real date on which Excel
dates are based is NOT 1900-01-01:
http://support.microsoft.com/default.aspx?scid=kb;en-us;214058
They claim that fixing this would be too difficult and doesn't caus
very many difficulties anyway, but apparently refuse to publish the
correct starting date in their documents. Where the other missing day
went I cannot say. It may have something to do with different
definitions for where a date is supposed to start.
-----Original Message-----
From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org
] On Behalf Of swertie
Sent: Tuesday, September 01, 2009 12:59 PM
To: r-help@r-project.org
Subject: [R] Date format in plot
Hello, I plot the abundance of a species in relation to the date. To
have the
date as a continous variable I put it in the format "standard" in
excel
(f.ex. 39939 means 06.05.2009). R uses 39939 on the x axis, but I
would like
to have "06.05". I tried to use as.Date as suggested in some
discussion but
I don't manage to use it, the returned date is not correct. Do you
have any
clue? thank you
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David Winsemius, MD
Heritage Laboratories
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______________________________________________
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